debris management
DESCRIPTION
Debris Management. Trashracks Screen Cleaning Systems. Trash racks - Criteria. “Open channel intakes shall include a trash rack which shall be kept free of debris.” “In certain cases, a satisfactory profile bar screen can substitute for a trash rack.” - PowerPoint PPT PresentationTRANSCRIPT
Debris Management
• Trashracks• Screen Cleaning Systems
Trash racks - Criteria
• “Open channel intakes shall include a trash rack which shall be kept free of debris.”
• “In certain cases, a satisfactory profile bar screen can substitute for a trash rack.”
• Comment - No trashrack would be rare situation - such as an on-river screen.
Trashracks
Trashracks
Trashracks
Trashrack Spacing
• Salmon can reject passage through small bar spacing's (3”).
• Recommend no smaller than 4”, but only go this small if there is a compelling reason to do so.
• Usually 6” – 9” spacing works pretty well.• Need to carefully assess what debris may be
present.
Trashrack Maintenance
• Install at a 1:5 (horizontal:vertical) slope (or flatter) for ease of cleaning.
• Provide easy access for cleaning.• Provide range of freedom for manipulating
debris.• Need to clean trashrack whenever head drop
exceeds a few inches, or whenever debris accumulates
Cleaning Systems
Main Criteria for Cleaning Systems
• Effective, reliable, proven, approved by NMFS• Head differential to initiate cleaning = 0.1 ft• Automated cleaning for most systems
Traveling Brush Cleaning System
Air Burst Cleaning System
Water Jet Cleaning System
Rotation – Vertical
Traveling Screens Cleaning System
Rotation – Drum Screen Cleaning System
Flow Distribution and Balancing
Approach flow – poor conditions
Approach flow - good conditions
Correcting Channel Configuration – Hydraulic Modeling
Channel Configuration – Approach Flow Conditions
Balancing Screen Approach Velocity
Balancing Screen Approach Velocity
Baffles for Adjusting Approach Velocity
Baffles for Adjusting Approach Velocity
Swift FSC – Offset Orifice Baffle Panels
Balancing Rotary Drum Screens
Cylindrical Screen Without Internal Baffles
Cylindrical Screen With Internal Baffles